Chewable tablets are widely used in the pharmaceutical industry for patients, such as children, who have who have difficulty swallowing conventional tablets or capsules. Children's TYLENOL.RTM. Chewable Tables are an example of a pediatric chewable acetaminophen tablet sold in the United States. These tables are packaged in bottles and have a flat face, beveled edge shape. Samples of these tablets obtained from retail locations had hardnesses (average of ten tablets) ranging from 5.3-13.1 kp or normalized hardnesses of 12.3-30.5 kp/cm.sup.2.
Many comercially avaialable pediatric chewable tablets contain active ingredients which are coated with polymers to mask their unpleasant taste. However, the forces used to compress these tablets can fracture the polymer coatings, which reduces the effectiveness of the tastemasking system.
Rapidly disintegrating dosage forms, such as those described in U.S. Pat. No. 5,464,632, issued Nov. 7, 1995, are also available for patients, particularly aged and pediatric patients, having difficluties swallowing tablets and caplets. However, rapidly disintegrating dosage forms currently available are highly friable, and require the use of special handling and costly packaging, e.g., specially designed blister packs, to prevent breakage or chipping of the tablets. These limitations significantly increase the product cost.
Tablet shape also affects tablet friability. T. Chakrabarti et al. in The Indian Journal of Pharmacy, Vol. 38, No. 3, pp. 62-65 (1975) disclose that lower friability was observed in beveled flat tablets followed by standard convex and plain flat tablets. Similarily, K. Sugimori et al. in Powder Technology, Vol. 58, pp. 259-264 (1989) report that capping occurs more often in convex-shaped tablets than flat faced tablets.
A need, therefore, exists for compressed, chewable tablets having improved taste, but which exhibit low friability so that they may be processed with standard bulk handling equipment and packaged in bottles.